Assessing the risk of vertebral osteoporosis.

Assessment of osteoporosis includes an accurate diagnosis, a consideration of the differential diagnosis, and prognostic assessment. Diagnosis of osteoporosis is based on bone mineral density (BMD) measurements and is defined as a BMD value that is 2.5 standard deviations or more below the average value in young healthy women (T score < or = -2.5 SD). Established osteoporosis is defined as a T-score of < or = -2.5 SD in the presence of a prior fragility fracture. The assessment of prognosis is important for defining intervention thresholds. Future fracture risk depends not only on BMD, but also on age. In addition, a variety of risk factors have been identified that increase fracture risk over and above that provided by BMD and age. Of particular importance is a prior fragility fracture, low body mass index and use of corticosteroids. The combination of independent risk factors permits a more accurate stratification of risk so that more patients at high risk can be identified. Risk of future fracture is optimally expressed as a probability. Ten-year fracture probabilities are appropriate for clinical use. The impact of BMD, age and other risks on fracture probability have recently been determined and provide a mechanism for optimising assessment of patients so that treatments can be efficiently directed to those most in need.